Lithographic projection apparatus equipped with extreme ultraviolet window serving simultaneously as vacuum window

Abstract

A lithographic projection apparatus has a discharge plasma radiation source that is contained in a vacuum chamber. The radiation source is to generate a beam of EUV radiation. A chamber wall of the vacuum chamber incorporates a channel structure comprising adjacent narrow channels separated by walls that are substantially parallel to a propagation direction of the radiation generated so as to pass the radiation from the vacuum chamber through the structure to another subsequent vacuum chamber. In the subsequent vacuum chamber, a much higher vacuum level (lower pressure) can be maintained than is present in the vacuum chamber of the radiation source.

We claim:  
     
       1. A lithographic projection apparatus comprising: 
       an illumination system constructed and arranged to supply a projection beam of radiation;  
       a mask table constructed to hold a mask;  
       a substrate table constructed to hold a substrate; and  
       a projection system constructed and arranged to image an irradiated portion of the mask onto a target portion of the substrate; and further comprising:  
       two vacuum chambers separated by a chamber wall incorporating a channel structure comprising adjacent narrow channels separated by walls that are substantially parallel to a propagation direction of said radiation so as to pass said radiation from one of said vacuum chambers to the other one, said propagation direction being substantially along an optical axis of said apparatus.  
     
     
       2. An apparatus according to  claim 1 , wherein a width of said channels increases or decreases along said optical axis in accordance with passing of a diverging or converging beam of radiation, respectively. 
     
     
       3. An apparatus according to  claim 1 , wherein said channel structure comprises a honeycomb structure. 
     
     
       4. An apparatus according to  claim 1 , wherein a cross-sectional dimension of said channels in a radial direction perpendicular to said optical axis is larger than another cross-sectional dimension of said channels in a tangential direction around said optical axis. 
     
     
       5. An apparatus according to  claim 4 , wherein said width in the tangential direction is in the range from 0.1 to 2 mm. 
     
     
       6. An apparatus according to  claim 4 , wherein said width in the radial direction is in the range from 5 to 50 mm. 
     
     
       7. An apparatus according to  claim 1 , wherein a length of said channel is in the range from 5 to 70 mm. 
     
     
       8. An apparatus according to  claim 1 , wherein said apparatus further comprises a radiation source contained in one of said vacuum chambers. 
     
     
       9. An apparatus according to  claim 1 , wherein said radiation source is a plasma source for generating extreme ultraviolet radiation. 
     
     
       10. An apparatus according to  claim 9 , wherein said radiation source is a discharge plasma source. 
     
     
       11. An apparatus according to  claim 1 , wherein the radiation is extreme ultraviolet radiation having a wavelength in the range from 0.5 to 50 nm. 
     
     
       12. A method of manufacturing a device using a lithographic projection apparatus comprising: 
       an illumination system constructed and arranged to supply a projection beam of radiation;  
       a mask table constructed to hold a mask containing a mask pattern;  
       a substrate table constructed to hold a substrate that is at least partially covered by a layer of radiation-sensitive material; and  
       a projection system constructed and arranged to image an irradiated portion of the mask onto a target portion of the substrate, and further comprising:  
       two vacuum chambers separated by a chamber wall incorporating a channel structure comprising adjacent narrow channels separated by walls that are substantially parallel to a propagation direction of said radiation so as to pass said radiation from one of said vacuum chambers to the other one, said propagation direction being substantially along an optical axis of said apparatus, said method comprising the step of:  
       using the projection beam of irradiation to project an image of at least a portion of the mask pattern onto a target portion on the substrate.  
     
     
       13. A device manufactured according to the method of  claim 12 . 
     
     
       14. A method according to  claim 12 , wherein said illumination system comprises a radiation source contained in one of said vacuum chambers. 
     
     
       15. A method according to  claim 12 , wherein said illumination system comprises a plasma source for generating extreme ultraviolet radiation. 
     
     
       16. A method according to  claim 12 , wherein said radiation source is a discharge plasma source. 
     
     
       17. A method according to  claim 12 , wherein a width of said channels increases or decreases along said optical axis in accordance with passing of a diverging or converging beam of radiation, respectively. 
     
     
       18. A method according to  claim 12 , wherein said channel structure comprises a honeycomb structure. 
     
     
       19. A method according to  claim 12 , wherein a cross-sectional dimension of said channels in a radial direction perpendicular to said optical axis is larger than another cross-sectional dimension of said channels in a tangential direction around said optical axis. 
     
     
       20. A method according to  claim 19 , wherein said width in the tangential direction is in the range from 0.1 to 2 mm. 
     
     
       21. A method according to  claim 19 , wherein said width in the radial direction is range from 5 to 50 mm. 
     
     
       22. A method according to  claim 12 , wherein a length of said channels is in the range from 5 to 70 mm. 
     
     
       23. A method according to  claim 12 , wherein the radiation is extreme ultraviolet radiation having a wavelength in the range from 0.5 to 50 nm.